1. Field of the Invention
The present invention is related to an electrical socket connector, and more particularly to a zero insertion force (ZIF) socket for electrically assembling an integrated circuit chip to a printed circuit board (PCB), wherein the ZIF socket has an actuation member for motivating a cover relative to a base of the ZIF socket.
2. Description of Related Art
Conventional ZIF sockets normally comprise a cover defining a plurality of upper passageways therein and slidably engaging with a base having a corresponding number of lower passageways retaining contacts therein. Optionally, the cover is driven to move with respect to the base by a screwdriver. U.S. Pat. Nos. 5,730,615 and 6,347,951 disclose such a driving mechanism for driving the cover to move on the base by inserting a screwdriver into slots defined in the cover and the base and pivoting the screwdriver to drive the cover to move. Such operation of the screwdriver is inconvenient. Furthermore, the screwdriver which is made of hard material (usually steel) can cause damage to either the cover or the base which is made of relatively soft material (usually plastics) when the screwdriver is used to drive the cover to move relative to the base.
In order to prevent the above-mentioned shortcoming, another ZIF socket having an actuation device for moving the cover attached with a CPU component relative to the base is provided. For instance, U.S. Pat. Nos. 4,498,725, 5,489,218 and 5,454,727, as well as page 35, page 5 and pages 2xcx9c3 of periodical entitled xe2x80x9cCONNECTOR SPECIFIERxe2x80x9d published respectively on November 1998, May 1998 and February 1995 all disclose such a typical ZIF socket including an actuation device. The actuation device consists of an exposed lever and an embedded rotation bar wherein the rotation bar joins the lever at one end and the bar further includes multiple cam sections or crank shaft sections. When the bar is oriented vertically to the base, the pins of the CPU component can be freely inserted into the socket. Successively, the operator manually pushes the lever downward to a horizontal position, during which the cam sections or the crank shaft sections of the rotation bar move the cover together with the CPU component horizontally and the pins of the CPU component are moved to engage with the corresponding contacts of the socket. Reversely, when the lever is moved from the horizontal position back to the vertical position, the cover together with the CPU component is moved horizontally in a reverse direction. Therefore, the engagement between the contacts of the socket and the pins of the CPU component is released, and the CPU component can be detached from the socket. Above-mentioned socket uses an actuation lever located along one side of the socket. However, the actuation lever increases the width of the socket. This is unfavorable in view of the minimization and compact trend of electronic components.
U.S. Pat. No. 6,338,639 discloses a socket having an actuation member configured to move a cover when the actuation member is rotated about a rotational axis. The actuation member is so designed that the rotational axis of the actuation member is parallel to the longitudinal sides of the socket along which the cover is moved relative to the base. The actuation member includes a cam assembly and an actuation lever. The actuation lever includes a handle and a leg. The actuation member is complicated in structure, which is disadvantageous from a cost consideration.
U.S. Pat. No. 6,280,223 discloses another socket having a simple driving mechanism. Nevertheless, when the socket is at a closed position, a high stress exists between the cam and a cover plate of the cover. The cam is made of zinc alloy. When the socket is exposed to an elevated temperature due to the operation of the CPU component mounted on the cover, the high stress causes the cam to creep because of the poor creep strength of zinc alloy. The creep of the cam causes the cam to deform from its original configuration whereby the cam can no longer achieve its requested stroke when it is rotated to move the cover relative to the base. Accordingly, the pins of the CPU component can not be moved to correctly engage with the contacts at the closed position or totally disengage from the contacts at the open position of the socket.
Hence, it is requisite to provide an electrical socket with an improved driving mechanism to overcome the above-mentioned disadvantages.
Accordingly, a first object of the present invention is to provide an electrical socket having an improved actuation member which can provide a effective stroke for the socket to ensure a reliable connection between the pins of an integrated circuit chip and conductive contacts of the socket.
A second object of the present invention is to provide an improved actuation member for a ZIF socket wherein the actuation member is convenient to manipulate by a user without increasing the width of the socket.
A third object of the present invention is to provide an improved actuation member for a ZIF socket which has a simple structure, thereby reducing cost.
In order to achieve the objective set forth, a electrical socket in accordance with the present invention is adapted for supporting an integrated circuit chip on a circuit board. The socket comprises a dielectric base defining an array of terminal cells, a plurality of conductive contacts received in the terminal cells, a cover slidably mounted on the base and an actuation member for moving the cover with respect to the base. The base defines a receiving space in one side thereof for receiving the actuation member and a receiving hole formed in an inner face of a lateral side portion thereof and communicating with the receiving space. The receiving space includes a receiving chamber and a receiving slot. The receiving hole has a step-shaped mating face forming an upper portion and a lower portion. The actuation member includes an operating handle and a cam shaft having a stepped shape and forming a cam member for moving the cover with respect to the base. The cam shaft has a contacting end for interacting with the mating face. The contacting end has a stepped shape and forms an upper portion and a lower portion. When the socket is at an open position, the upper portion of the contacting end of the cam shaft bears against the upper portion of the mating face of the receiving hole. When the socket is at a closed position, the upper and lower position of the contacting end of the cam shaft bear against the lower and upper portion of the mating face of the receiving hole, respectively.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.